Minsoo Chun, Jaewon Hong, Chang-Heon Choi, JinHwaChoi, Jung-in Kim, Hong-Gyun Wu, Minjae Choi, NaYoung Jang, So-YeonPark
Medical Physics
2025.07
This study presents MZ CUBE, a newly developed multipurpose phantom designed to assess both image quality and geometrical accuracy in image-guided radiotherapy.
The phantom is a 16 × 16 × 16 cm³ cube made of acrylonitrile butadiene styrene and designed to evaluate HU constancy, HU uniformity, spatial integrity, spatial resolution, low contrast resolution, and geometrical accuracy. Two CT simulators (Big Bore RT and Discovery RT Gen3) and two cone-beam CT (CBCT) systems (XVI and OBI) were used for verification alongside commercial phantoms (ACR 464 and CatPhan 504).
HU constancy differences were within 3 HU, and uniformity was within 1 HU for CT and 2 HU for CBCT, based on repeated MZ CUBE measurements. Spatial resolution with the MZ CUBE was 7 lp/cm (Big Bore RT), 8 lp/cm (Discovery RT Gen3), 7 lp/cm (XVI), and 8 lp/cm (OBI). The minimum discernible disk diameters were 7, 5, 6, and 6 mm, respectively. Geometrical accuracy was confirmed with translational offsets below 1 mm and rotational deviations below 0.2° for both CBCT systems.
MZ CUBE enables comprehensive image quality and geometric accuracy evaluation in a single scan, offering an efficient and cost-effective solution for radiotherapy QA.
